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CASE REPORT |
Pediatrics, Hôpital Universitaire des Enfants Reine Fabiola, U.L.B., 15, Avenue J.J. Crocq, 1020 Brussels, Belgium1 Medical Genetics, V.U.B., Brussels, Belgium2 Surgery, Institut J. Bordet, U.L.B., Brussels, Belgium3 Nuclear Medicine4 Clinical Chemistry, CHU Brugmann, U.L.B., Brussels, Belgium
(Correspondence should be addressed to C Brachet; Email: cecile.brachet{at}huderf.be)
Abstract
Objective: Familial hypocalciuric hypercalcaemia (FHH) is clinically characterized by mild to moderate parathyroid hormone (PTH)-dependent hypercalcaemia, autosomal dominant pattern of inheritance, and normal to frankly reduced urinary calcium excretion in spite of a high serum calcium (clearance (Ca)/clearance (Cr)<0.01). FHH has a benign course and should be differentiated from primary hyperparathyroidism. It is usually caused by a heterozygous loss-of-function mutation in the calcium-sensing receptor gene (CASR).
Design: We report the case of a 16-year-old patient with hypercalcaemia and a mixed family history of parathyroid adenoma and mild hypercalcaemia. Serum calcium was 14 mg/dl with a serum iPTH of 253 pg/ml.
Results: A neck 99mTc-sesta MIBI tomoscintigraphy showed a definite hyperactivity in the left upper quadrant. A surgical four-gland exploration confirmed a single parathyroid adenoma. After surgical resection of a left superior parathyroid adenoma, the patient's hypercalcemia improved but did not normalize, returning to a level typical of FHH. An inactivating mutation in exon 4 of the CASR gene, predicting a p.Glu297Lys amino acid substitution was found.
Conclusions: Thus, this 16-year old patient presented with the association of FHH and a single parathyroid adenoma. The young age of the patient and the association of parathyroid adenoma and FHH in his grandmother argue for a causal link between CASR mutation and parathyroid adenoma in this family. This case contributes to illustrate the expanding clinical spectrum of CASR loss-of-function mutations.
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